Safety gate for presses

ABSTRACT

A press having a ram adapted to move vertically toward a die surface, including a safety gate automatically swingable to move in front of the die facade. The gate is mounted at the end of a pair of parallel arms pivotally connected to the ram so that the arms and gate are conjointly movable in the vertical direction with the ram. The arms are simultaneously linked to the frame of the press by a crank lever system so that the downward vertical movement of the ram swings the gate in front of the die facade in advance of the closing of the ram.

United States Patent Komori et al.

[451 Aug. 29, 1972 [54] SAFETY GATE FOR PRESSES [73] Assignee: said Masahim Komori, by sold Takehlko Kornorl [22] Filed: Dec. 3, 1970 [21] Appl. No.: 94,699

[30] Foreign Application Priority Date Dec. 18, 1969 Japan ..44/ 119693 Jan. 17, 1970 Japan ..45/4265 [52] US. Cl ..100/53, 74/615 [51] Int. Cl. ..B30b 15/00 [58] Field of Search........74/6l2, 613, 614, 615, 616; 100/53; 83/397; l8/DIG. 45; 192/133, 135

[56] References Cited UNITED STATES PATENTS 1,549,740 8/1925 Ashby..........................74l6l5 1,439,818 12/ 1922 Horder ..74/615 2,443,726 6/ 1948 Dickerman ..74/61 5 1,733,227 10/ l 929 Jones ..74/615 FOREIGN PATENTS OR APPLICATIONS 143,471 5/1920 Great Britain ..74/6l5 1,006,451 10/1965 Great Britain...............l0O/53 Primary ExaminerBilly J. Wilhite Attorney-Kurt Kclman 57 ABSTRACT A press having a ram adapted to move vertically toward a die surface, including a safety gate automatically swingable to move in front of the die facade. The gate is mounted at the end of a pair of parallel arms pivotally connected to the ram so that the arms and gate are conjointly movable in the vertical direction with the ram. The arms are simultaneously linked to the frame of the press by a crank lever system so that the downward vertical movement of the ram swings the gate in front of the die facade in advance of the closing of the ram.

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saw u or 5 INVENTORS mnsnnmo 00mm BY rnnemxo KomRl Kw ro HG EMF SAFETY GATE FOR PRESSES The present invention relates to safety devices for presses, rams and the like, and in particular to an automatic gate means operable in direct response to the descent of the ram to block entry to the interface between the dies.

Protective devices, such as nets, gates, fences, etc., have been used to prevent accidental insertion of the hand or arm of an operator between the die faces. Such devices, however, require manual control and concentration upon the part of the operator in order to be used effectively.

In co-pending US. Pat. No. 3,641,841, filed Mar. 13, 1970, there is disclosed a gate means automatically controlled by the operation of the press to be rapidly and quickly interposed between the operator and the dies. The automatic devices disclosed in the co-pending application are suitable and efficient for many operations; however, the mechanism for moving the gate is somewhat complex and expensive so that it is generally economical only for large presses.

It is an object of the present invention to provide a safety mechanism for a press which is simple in construction and which is highly economical.

It is another object of this invention to provide a safety mechanism for a press which is automatically operable in response to the direct vertical movement of the ram.

It is a further object of the invention to provide a safety device having a gate which is responsive to the vertical movement of the ram and which is provided with a crank mechanism effecting increased speed so that the gate may be interposed between the operator and the facade of the die prior to the actual closing of the die.

These objects, as well as others, together with numerous advantages are obtainable by the present invention, specific embodiments of which are fully described hereinafter.

The present invention is directed to a press having a vertically movable ram means disposed above a base with which it cooperates to provide engaging die surfaces. The press is provided with a safety mechanism comprising a gate pivotally mounted at one end of a parallel arm system secured at the other end directly to the ram. The arm system includes a crank mechanism linked and fixed to the frame of the machine so that, on downward movement of the ram, the crank mechanism causes the arm levers to swing the gate into a position in front of the dies while, on upward movement of the ram, the gate is caused to swing outwardly to the side of the press.

In the preferred form of this invention, the crank mechanism and parallel arm system are arranged so that an over-the-center effect is obtained whereby the movement of the ram causes an accelerated and positive action on the gate, insuring its swift and irreversible movement in front of the die facade. Spring means resiliently bias the arm system and crank mechanism.

In one form of the invention, a resilient buffer or dash-pot mechanism is provided to enable the movement of the gate to be more responsive to any obstruction which may be in its path.

Preferred embodiments are described in detail in the following description, taken in conjunction with the accompanying drawing wherein Fig. l is a front elevational view, in schematic representation, of a ram press embodying the principles of the present invention;

FIG. 2 is an enlarged perspective view of the gate and crank mechanism assembly, as seen in FIG. 1;

FIG. 3 is a view showing the movement of the gate mechanism during operation of the press;

FIG. 4 is a view similar to FIG. 1 showing a modified version of the crank mechanism assembly; and

FIG. 5 is an enlarged perspective view of the modified version shown in FIG. 4.

The present invention may be effectively embodied in any well-known and conventional press or stamping machine. As seen in the drawing, such a machine may comprise a base B supported on a plurality of legs L on i which a die member D rests. Mounted above the base is a frame F in which a ram R carrying die D, is mounted for reciprocation in a vertical direction into and out of engagement with die D The ram is generally of heavy weight and is moved or operated by suitable drive means, such as an hydraulic, pneumatic or electric motor. Suitable electrical or other automatic control means are provided, the details of which are omitted since the same are conventional and wellknown to those skilled in this art. The particular details of the controls are of little consequence in understanding the present invention since any conventional ram or press may benefit from the present invention.

As seen in FIGS. 1 and 3, the safety gate is generally embodied in a closure assembly G swingable by a crank mechanism S between an open" position to the side of the die facade (seen in dotted lines in FIG. 3) to a closed" position interposed in front of the facade of the two dies (seen in full line in FIG. 3). 1n the latter position, the gate prevents entry by the operator to the interface between the dies.

The present gate 10 may be made of any suitable material, such as hard rubber, plastic or metal, in the shape of a preferably rectangular plate. The gate is smoothly finished and designed not to harm or injure the operator should it come in contact with him. The gate 10 is attached to the crank mechanism S which comprises a pair or parallel arms 12a, 12b which, as seen in FIG. 2, are pivotally connected to the rear face of the gate 10 by means of a pair of pins 140 and 14b, respectively. The lower ends of the arms 12a, 12b and the pivot pins 14a, 14b are secured by a backing plate 16 attached to the gate 10. The upper ends of the arms 12a, 12b are secured by pivot pins 18a, 18b, respectively, in a fixed retaining plate 20 secured to the ram R of the press. The fixed retaining plate 20 is mounted on a bracket 22 so as to be horizontally adjustable. The bracket 22 is itself fixed to the ram R so as to be vertically adjustable. The horizontal and vertical adjustments for the plate 20 and bracket 22 preferably comprise interacting slots and bolts, as illustrated. Other adjustable fastening means may, however, be employed.

Secured to the upper end of the arm or directly to its pivot pin 18a is an angularly extended link 24. The link 24, together with the arm 12a, provide an integral crank lever similar to the conventional bell crank. Pivotally connected to one end of the crank arm 24 is a link 26 which is connected at its other end to a slide rod 28. The upper end of the rod (FIG. 1) is provided with a releasable bolt 30 slidably retained within the slot 32 of a bracket 34 secured at its upper end by a bolt 36 directly to the stationary frame of the press.

integrally fixed to the pivot pin 18a and the crank lever 24 is a wedge-shaped (triangular) stop member 38 which is adapted to make endwise abuttment with the link 26 when the gate is in its open" position, as seen in FIG. 1. Finally, a spring 40 is connected to the arm 12a and to the retaining plate so as to bias the arms normally into the open position.

The operation of the safety device is as follows:

Initially, with the ram in an upward or open" position, the retaining plate 20 and the slide rod 28 are respectively fixed to the ram and frame so that the gate and the parallel arms 12a and 12!) extend as far to the side of the press as is necessary for the gate 10 to clear the facade and in conformance with the distance between the die D, and D, so that, on subsequent lowering of the ram, the gate 10 will be able to move into a position in front of the dies. Such adjustment, of course, is made by loosening and then tightening the fastening means holding the plate 20 and/or bracket 22 to the ram. The bolt 30 holding the ram 28 to the bracket member 34 is also adjusted.

Cyclical operation of the ram can then be effected, as desired. During the downward movement of the ram the plate 20 is conjointly carried downwardly, causing an elongation of the slide rod 28 and the connecting link 26, as seen in FIG. 3. This causes the crank lever 24 and the parallel arms 12a, 12b to swing counterclockwise. Simultaneously, the abutting edges of the connecting link 26 and the triangular stop member 38 continue to be pressed together until the elongation of the rod 28 and link 26 is such that the force against the abutting edges causes the crank to react in an over-thecenter effect resulting in the swift and positive completion of the swing of the gate 10 into the closed" position. This positive movement of the gate 10 is effected prior to the actual engagement of the dies D and D thus closing the facade before the workpiece is engaged. Further, the positive movement of the gate 10 created by the crank mechanism is such that it would remove from in front of the die facade any hand, arm or other obstruction which may be accidentally in the way. The timing of the movement of the gate 10 is, of course, dependent on the adjustments of the retaining plate 20, brackets 20, 22 and the slide rod 28.

On upward movement of the ram, in the continuing cycle of the press operation, the retaining plate 20 carries the swing assembly upwardly so as to relax the tension and stretch between the rod 28 and the link 26. As this tension is relaxed, spring 40 biases the arms 12a and 12b so as to cause the gate to swing from the facade to its outward or open" position. As the rod 28 and link 26 relax, the abutting edge of the link 26 and the triangular stop member 28 again engage, causing a positive action on the crank lever 24 and forcing the gate 10 in its open" position. Thus, the die facade is quickly opened, freeing the interface between the die and the ram for removal of the workpiece and for the insertion of another workpiece, and the repetition of the press operating cycle.

From the foregoing it will be seen that there is provided a simple yet very effective mechanism for swinging a safety gate in front of the die facade in direct response and consequence to the vertical movement of the ram. The device is highly effective, being swift in operation and adjustable to assure placement of the gate in front of the die facade prior to the actual closing of the ram on the die and with sufficient force to remove from in front of the die facade any interfering member, such as the arm of the operator.

In FIGS. 4 and 5, a modified version of the present invention is shown. ln these figures like reference numerals are employed for parts and elements which are similar to those described in FIGS. 1 through 3 since the ram press and the gate is constructed, arranged and functions in the manner previously described. In this modification, the connecting slide rod by which the crank mechanism is connected to the frame of the press and the connecting link are both replaced by a springloaded buffer means and an adjustable link, which provides a greater degree of adjustability and resilient operation of the device so that the over-the-center effeet and the positive operating effect of the crank means may be more effectively obtained.

As seen in FIGS. 4 and 5, the crank lever 24 is connected to a connecting link 42 which is provided with a plurality of holes 44. Retained in a selected one of the holes 44 is the end of the connecting rod 46 which itself is connected pivotally to the end of a piston rod 48 located within a cylinder 50. The piston rod 48 is provided with a head 52 which is biased by a spiral compression spring 54 which abuts against the lower end of the cylinder and the head 52 of the piston. The upper end of the cylinder is retained by a threaded bolt 56 provided with a nut 58. The threaded bolt 56 is fixedly secured to the frame F of the press. By adjusting the bolt 58, in the manner of the corresponding bracket seen in FIG. 1, and by positioning the connecting rod 46 in a selected hole 44 in the connecting link 42, the crank mechanism is more precisely adjusted to the required location for the open" and/or closed position. In general, the device shown in FIGS. 4 and 5 functions in exactly the same manner as the device seen in FIGS. 1 through 3. On downward descent of the ram R, the retaining plate 20 again carries the parallel arms 12a, 12b and the gate 10 downwardly, stretching or elongating the link 42 and the connecting rod 46. Since the connecting rod 46 is attached to resiliently biased piston rod 48, the movement of the crank mechanism as a whole is buffered so that, rather than being fixed as in the other embodiment to a defined position, it is constanfly urged by the force of the compression spring upwardly and, therefore, into the elongated position. Thus, the further the ram R moves downwardly, the stronger the elastic force of the compression spring 54 becomes and the stronger the urge for the connecting rod 46 and connecting link 42 to elongate themselves. The parallel arms 12:, 12b and the gate 10 are more strongly urged to complete their swing, even by the slightest downward movement of the ram, to its closed position. This spring loading of the gate 10 insures a swifter action with a more positive force to it. This is of great benefit since it easily overcomes any residual or contrary force which might be imposed upon it by an accidental obstruction, such as the arm of the operator of the machine press. in addition to providing a greater degree of adjustability, the buffering mechanism permits a more precise location of the gate and a safer closure since the spring loading of the gate provides a bufier so resilient that the gate will not close with a sharp and sudden force upon the arm of the operator.

0n upward movement of the ram, the retaining plate 20 again carries the parallel arms 12a, 12b and the gate upwardly, relaxing the stretch or elongation of the connecting link 42 and connecting rod 46, permitting the biasing spring to move the gate to its "open position. This movement is further accentuated by the action of the compression spring 54 on piston rod 48, urging the piston rod upwardly and causing the crank lever 24 to abut against the triangular stop 38 to effect the over-the-center action on the return or upward stroke.

The adjustment holes 44 provided in the connecting link 42 enable the present mechanism to be employed on presses which may have variable strokes. By adjusting the position of the connecting rod 46 in the connecting link 42 and/or the position of the cylinder 50 with respect to the frame F, the apparatus may be made to accommodate different distances of ram travel. In other respects, the mechanism shown in FIGS. 4 and 5 functions and operates as that in FIGS. 1 to 3.

It will be apparent to those skilled in this art that various modifications and changes may be made to the actual structure described. it is, therefore, intended that the described embodiments be illustrative only of the invention and not limiting in scope.

What is claimed:

1. Safety apparatus for a press or the like, which comprises a frame, a base supported on said frame, a ram disposed above the base and mounted to reciprocate vertically with respect thereto, the base and ram carrying mating dies for manipulating a workpiece therebetween on the downward movement of the ram, said apparatus comprising a gate, movable support means for moving said gate between a first position to the side of said ram to expose said dies and to a second position in front of said dies to shield the same, said movable support means being directly connected to said ram so as to be shiftable from said first to said second position on the downward movement thereof and from said second to said first position on upward movement thereof, and said support means comprising a pair of parallel arms, said arms being pivoted at one end to said gate and at the other end to said ram, one of said arms having an angularly extending crank lever and connecting link means joining said crank lever to the frame whereby, on movement of said ram, said crank lever causes said arms to move between the first and second positions.

2. The apparatus of claim 1, wherein said arms and crank lever have stop means adapted to abut against the connecting link means during movement thereof to effect an over-the-center action.

3. The apparatus of claim 2, including resilient means for normally biasing said gate into said first position.

4. The apparatus of claim 3, wherein said connecting link means comprises a bracket affixed to said frame, and a rod extending outwardly therefrom and adjustably affixed thereto, said rod being linked to said crank lever.

S. The apparatus of claim 4, including link means co nectin sai r d to said c ankl ver, said link me ns beii'ig pro1de with a plurality of iioles and means for connecting the end of said rod in a selected one of said holes to adjust the length thereof.

6. The apparatus of claim 5, wherein said connecting link means includes resilient buffer means whereby said connecting rod is variably movable with respect to said frame.

7. The apparatus of claim 6, wherein said resilient buffer means comprise a piston and cylinder, and a spring biasing said piston within said cylinder. 

1. Safety apparatus for a press or the like, which comprises a frame, a base supported on said frame, a ram disposed above the base and mounted to reciprocate vertically with respect thereto, the base and ram carrying mating dies for manipulating a workpiece therebetween on the downward movement of the ram, said apparatus comprising a gate, movable support means for moving said gate between a first position to the side of said ram to expose said dies and to a second position in front of said dies to shield the same, said movable support means being directly connected to said ram so as to be shiftable from said first to said second position on the downward movement thereof and from said second to said first position on upward movement thereof, and said support means comprising a pair of parallel arms, said arms being pivoted at one end to said gate and at the other end to said ram, one of said arms having an angularly extending crank lever and connecting link means joining said crank lever to the frame whereby, on movement of said ram, said crank lever causes said arms to move between the first and second positions.
 2. The apparatus of claim 1, wherein said arms and crank lever have stop means adapted to abut against the connecting link means during movement thereof to effect an over-the-center action.
 3. The apparatus of claim 2, including resilient means for normally biasing said gate into said first position.
 4. The apparatus of claim 3, wherein said connecting link means comprises a bracket affixed to said frame, and a rod extending outwardly therefrom and adjustably affixed thereto, said rod being linked to said crank lever.
 5. The apparatus of claim 4, including link means connecting said rod to said crank lever, said link means being provided with a plurality of holes and means for connecting the end of said rod in a selected one of said holes to adjust the length thereof.
 6. The apparatus of claim 5, wherein said connecting link means includes resilient buffer means whereby said connecting rod is variably movable with respect to said frame.
 7. The apparatus of claim 6, wherein said resilient buffer means comprise a piston and cylinder, and a spring biasing said piston within said cylinder. 